Sahih Muslim | Book 8 | Hadith Number 3395

Narrated by 'Aisha (Allah be pleased with her)
'Aisha (Allah be pleased with her) reported that Allah's Messenger (may peace be upon him) was with her and she heard the voice of a person seeking permission to enter the house of Hafsa. 'Aisha (Allah he pleased with her) said: Allah's Messenger, he is the person who seeks permission to enter your house, whereupon Allah's Messenger (may peace be upon him) said: I think he is so and so (uncle of Hafsa by reason of fosterage). 'Aisha said: Messenger of Allah, if so and so (her uncle by reason of fosterage) were alive, could he enter my house? Allah's Messenger (may peace be upon him) said: Yes. Fosterage makes unlawful what consanguinity makes unlawful.